Flagging of twigs may be caused by insects, disease, squirrels or strong winds. A very common cause of flagging, however, is cicada insect activity.
This time of year it is not uncommon to see tips of branches and leaves turning brown in trees. There may be a number of reasons for this "flagging" of twigs, including insects, disease, squirrels or strong winds that may have broken the branch.
A very common cause of flagging, however, is cicada insect activity. There are nearly 2,000 species of cicadas found throughout the world in temperate and tropical climates. Cicadas are sometimes called locusts, but they are not part of the grasshopper family.
Cicadas are large, flying insects with prominent, well-spaced eyes and transparent wings with very distinct veins. Cicadas have a loud buzzing song, usually generated by the male during the courtship ritual. This song can be quite robust, reaching 120 decibels at close range.
Once mating occurs, the female cicada cuts a slit in a tree branch to lay her eggs. This egg-laying activity sometimes girdles or breaks the branch, hence the occurrence of flagging in trees. The young nymphs hatch from the egg in the fall and drop to the ground where they burrow into the soil.
Some cicadas emerge on a fairly routine schedule annually or in cycles of two to eight years, while others spend a long time underground, emerging every 13 to 17 years. It is this longer-lived or periodic cicada that is most famous due to the sheer volume of insects that emerge on 13- to 17-year cycles. The last periodic cicada emergence occurred in 2004 in Frederick County.
Scientists believe that cicadas developed the various life cycles as a survival mechanism. Many species of birds eat cicadas and fried cicada is considered a delicacy in China.
Article by FCFCDB
Nature Notes for 8/26/2012